The patent document EP 0570970 discloses a drier comprising an upper conveyor belt that unloads by gravity the product to be dried on a lower conveyor belt, the drier using an upward air flow for the drying of the products conveyed by the belts. This document recommends forcing the air circulation upwards for reducing the quantity of powder or suspended particles dragged by the air flow.
This drier comprises reheating means for reheating the used air, means towards which the air is conducted after going through the lower belt and means through which the air is forced to circulate before being redirected towards the upper belt.